Those cities are primarily safe because of culture and infrastructure.

I am currently working in the Netherlands, not Amsterdam...but further north.I ride a bike to/from work every day, as do about 400 others who work in my building.

CULTURE cannot be overstressed.Nearly everyone who drives here, grew up riding a bike here, and probably were presented with a bicycle about the same time they leared to walk.Driver's license age is 18, and as everyone is ON a bike, daily until that age, as drivers they are very, very, very aware of bicycles.Bicycles almost always have and are given right of way.A bicycle on the sidewalk is regarded much the same as if one drove a motorcycle on the sidewalk- why would you? A bicycle is a Road Vehicle...and in the US (overall) it is just not considered that way